Until relatively recently it has been generally thought that a person was capable of hearing audio frequency vibrations only with the ears and that it was necessary to utilize the ear structure for effective communication. It has also been known that the body has cutaneous nerve receptors which sense mechanical vibrations in the air and transmit those vibrations to the brain, by-passing the ear structure.
In the medical profession, it has been found that many people who are partially deaf are afflicted with sound distortion, so that even though they hear particular sounds or words, the sounds or words become so distorted by the inner ear, they are indecipherable. Accordingly, if such a deaf person can be trained to by-pass the inner ear in order to "hear", this distortion may be eliminated.
A cutaneous communication device for transmitting audio information to the cutaneous nerve receptors located at the wrist of a user to allow the user to by-pass the ear structure and "hear" the audio information is described in U.S. Pat. No. 4,139,742 to Walker which has been assigned to the assignee of the present application. This device includes a conventional microphone connected by a cable and jack to an audio frequency amplifier. The amplifier provides signals to a mechanical transducer assembly mounted on a band to be worn around the wrist of a user. The transducer assembly includes a plunger which projects outwardly of the transducer assembly housing to contact the skin. The plunger moves towards and away from the skin when signals are applied to the transducer via the amplifier in response to input audio signals received by the microphone.
The transducer assembly operates to move the plunger in a vibrational pattern analogous to the audio signals received by the microphone. The cutaneous nerve receptors at the wrist of the user discriminate between the vibrations caused by the plunger and extraneous noise to allow the brain to interpret the audio signals received by the microphone. This permits audio communication to occur without use of the inner ear. Although the operation of this device is satisfactory, it is always desirable to enhance performance and reduce complexity and size.
In addition to assisting the hearing impaired, there are many other situations in which it is difficult or undesirable to communicate verbally by transmitting messages through the air. For example, it is extremely difficult to communicate audibly in industrial plants where ear muffs are worn. Also, motorcycle riders and their passengers have difficulty talking to one another because of noise generated by both the motorcycle engine and the wind. Furthermore, there may be situations in which a person needs to receive both audio communication and cutaneous nerve communication. For example, spoken messages can be received by radio receiver and transmitted cutaneously to the brain while the person is otherwise occupied or otherwise communicating verbally. Such a device could have use in a "bell boy" call director type of communication system. Moreover, when conducting surveillance it is often undesirable to communicate verbally with other parties although communication between the parties is desirable.
Accordingly, it is an object of the present invention to provide a novel communication device for transmitting audio information to a user and a transducer for use therein.